Wire with platinum composition for contacting temperature sensors

ABSTRACT

The invention relates to a wire for electrically contacting temperature sensors, the wire consisting of at least 50 wt % of a platinum composition, the platinum composition containing between 2 wt % and 3.5 wt % tungsten, up to 47.95 wt % of at least one precious metal selected from the group consisting of rhodium, gold, iridium and palladium and mixtures thereof, between 0.05 wt % and 1 wt % oxides of at least one non-precious metal selected from the group consisting of (i) zirconium, (ii) aluminum and (iii) zirconium and at least one element selected from aluminum, yttrium and scandium, and, as the remainder, at least 50 wt % platinum including impurities. The invention also relates to a temperature sensor having such a wire, and to a method for producing such a wire and such a temperature sensor.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of European Application No. EP20199749.1 filed Oct. 2, 2020, the entire contents of which areincorporated by reference herein

DESCRIPTION

The invention relates to a wire for electrically contacting temperaturesensors, comprising a platinum composition, to a temperature sensorhaving at least one such wire, and to a method for producing such a wireand such a temperature sensor. The platinum composition consists of atleast 50 wt % platinum (Pt) and 2% to 3.5 wt % tungsten (W) and contains0.05% to 1 wt % of oxides of the non-precious metals zirconium (Zr) oraluminum (Al). The platinum composition may also contain up to 47.95 wt% of at least one of the precious metals rhodium, gold, iridium andpalladium and may also contain, as part of the oxides, oxides of thenon-precious metals yttrium (Y) and scandium (Sc) and, as the remainder,platinum including impurities.

Dispersion-hardened platinum wire (Pt DPH-A wire) is currently popularfor use for electrically contacting thermistors and other temperaturesensors under extreme conditions. These temperature sensors are used,inter alia, in the automotive industry for temperature measurement inexhaust gas lines or exhaust gas streams of cars (for example, todetermine catalytic converter temperatures and/or exhaust gastemperatures). Under operating conditions, there are temperatures of1,000° C. and higher, in a corrosive exhaust gas atmosphere. During theelectrical contacting of the temperature sensors and the production ofthe wires, temperatures of 1,300° C. to 1,600° C. can occur. Such atemperature sensor is known, for example, from DE 102 11 029 B4. Inaddition to the thermal stress on the wire, there is also a mechanicalstress on the component, for example due to vibrations. Whiledispersion-hardened platinum is characterized by excellent corrosionresistance, it often has inadequate mechanical properties.

The production, the processing and the physical properties ofdispersion-hardened platinum compositions of this kind are known, forexample, from GB 1 280 815 A, GB 1 340 076 A, GB 2 082 205 A, EP 0 683240 A2, EP 0 870 844 A1, EP 0 947 595 A2, EP 1 188 844 A1, EP 1 295 953A1, EP 1 964 938 A1, U.S. Pat. Nos. 2,636,819 A, 4,507,156 A, DE 23 55122 A1, WO 81/01013 A1 and WO 2015/082630 A1.

Dispersion-solidified platinum compositions are usually produced bypowder metallurgy or melting metallurgy by alloying zirconium (Zr) andoptionally other non-precious metals such as yttrium (Y) or scandium(Sc), which are oxidized in a subsequent oxidation process to formzirconia (ZrO₂), yttria (Y₂O₃) and scandia (SC₂O₃).

It is therefore the object of the invention to overcome the drawbacks ofthe prior art. It is intended to retain the advantages of wireconsisting of dispersion-hardened platinum as far as possible. Inparticular, a wire made of or with a platinum composition and atemperature sensor electrically contacted therewith are intended to beprovided, it being intended for the platinum composition and the wire tobe able to be produced in as inexpensive and uncomplicated a manner aspossible. In addition, the wire is intended to have the highest possiblestrength and elongation at break. As a result, the wire can be processedin a temperature sensor, and the sensor can be used in extremeconditions, such as those found in an exhaust line of a car.

By means of the invention, the mechanical properties are intended to beimproved, and the costs are intended to be reduced. In general, wiresconsisting of or containing platinum compositions of this kind are usedprimarily at high application temperatures in corrosive conditions incombination with significant mechanical stress, such as contact wiresfor electrically contacting temperature sensors in exhaust gas streamsor engines.

The objects of the invention are achieved by a wire for electricallycontacting temperature sensors, the wire consisting of at least 50 wt %of a platinum composition, the platinum composition containing

-   1) 2 wt % to 3.5 wt % tungsten,-   2) up to 47.95 wt % of at least one precious metal selected from the    group consisting of rhodium, gold, iridium and palladium and    mixtures thereof,-   3) 0.05% to 1 wt % of oxides of at least one non-precious metal    selected from the group consisting of (i) zirconium, (ii) aluminum    and (iii) zirconium and at least one element selected from aluminum,    yttrium and scandium, and,-   4) as the remainder, at least 50 wt % platinum including impurities.

According to the invention, oxides of zirconium or oxides of zirconiumand oxides of yttrium and/or oxides of scandium are preferred as the0.05 wt % to 1 wt % of oxides of the at least one non-precious metal.

The platinum composition is preferably a platinum-based alloy. Aplatinum-based alloy is understood to be an alloy which consists of atleast 50 at. % platinum.

Preferably, 0.1 wt % to 0.7 wt %, particularly preferably 0.2 wt % to0.5 wt % of the oxides of the at least one non-precious metal arecontained in the platinum composition. High proportions of oxides of thenon-precious metals result in higher strengths of the wire undermechanical stress. Wires containing platinum compositions with lowproportions of non-precious metal oxides exhibit advantages in terms ofprocessability, for example weldability or moldability, of the platinumcomposition for producing the wires.

According to a further development of the present invention, it may beprovided that the platinum composition contains up to 30 wt % of atleast one of the precious metals selected from the group consisting ofrhodium, gold, iridium and palladium and mixtures thereof, preferablycontaining 0.5% to 30 wt % of at least one of these precious metals,particularly preferably containing 1% to 20 wt % of at least one ofthese precious metals, most particularly preferably containing 1% to 10wt % of at least one of these precious metals.

Furthermore, it may be provided that the platinum composition comprisesup to 10 wt % gold, up to 30 wt % rhodium, up to 30 wt % iridium or upto 47.95 wt % palladium as the at least one precious metal.

The platinum composition may be a pure platinum-tungsten composition,except for impurities that are usual or result from the productionprocess, in which the oxides of the at least one non-precious metalzirconium or aluminum or zirconium and aluminum, yttrium and/or scandiumare distributed. Furthermore, however, the platinum composition may alsocontain other precious metals, namely rhodium, gold, iridium andpalladium, the platinum composition preferably being a platinum-basedalloy in this case.

The impurities in the components of the platinum composition areunderstood to be usual impurities which get into the starting materialdue to and as part of the design process or which could not be (furtheror completely) removed from the raw materials with reasonable effort.

Preferably, it may be provided that the platinum composition is notproduced by powder metallurgy.

In wires according to the invention, it may be provided that theplatinum composition is dispersion-hardened.

A dispersion-hardened platinum composition of the composition accordingto the invention has precipitates of the oxides of the at least onenon-precious metal in the matrix of platinum (platinum group metal) andtungsten, which results in hardening of the platinum composition.

Dispersion hardening improves the mechanical properties of the wire.

It may also be provided that the total proportion of the impurities inthe platinum composition is at most 1 wt %, preferably at most 0.5 wt %.

This ensures that the physical properties of the platinum compositionand thus of the wire are not influenced by the impurities or areinfluenced by the impurities as little as possible.

Furthermore, it may be provided that the wire consists of at least 90 wt% of the platinum composition, or the wire consists of the platinumcomposition, except for an outer coating or plating, or the wireconsists of the platinum composition.

This ensures that the platinum composition determines the physical and,in particular, the mechanical properties of the wire. If a coating ispresent, this can specifically improve the electrical properties and inparticular the electrical contactability of the wire or serve as ashield against corrosive media.

Furthermore, it may be provided that at least 50 mol. % of the oxides ofthe at least one non-precious metal are present as cubic zirconiastabilized with yttria and/or scandia, and preferably at least 80 mol. %of the oxides of the at least one non-precious metal is present as cubiczirconia stabilized with yttria and/or scandia.

It has been found that the oxygen diffusibility along the oxides can beincreased by these measures, and thus the wire can be hardened byoxidation of the non-precious metals in a relatively short time in anoxidizing atmosphere. As a result, high oxygen diffusibility through theoxidation regions and therefore good oxidizability of the non-preciousmetals zirconium, yttrium and scandium is achieved in the platinumcomposition. As a result, the platinum composition can be hardened in aparticularly short time by oxidative precipitation. In addition, aplatinum composition or wire with particularly high tensile strength andelongation at break can thus be produced. In addition, stabilization ofthe cubic modification of the zirconia minimizes stress due to thermalshock.

Preferably, it may also be provided that the platinum composition isproduced by melting metallurgy and subsequently oxidized by atemperature treatment in an oxidizing medium such that the non-preciousmetals contained in the platinum composition are completely oxidized,the platinum composition preferably being subsequently formed into thewire and particularly preferably annealed before and/or after this.

As a result, a particularly well-hardened platinum composition or aparticularly well-hardened wire are produced.

It may be provided that the platinum composition contains at least 80 wt% platinum including impurities, the platinum composition preferablycontaining up to 17.95 wt % rhodium.

With the higher platinum content, fewer other precious metals areincluded in the platinum composition, and the platinum composition istherefore less expensive.

It may also be provided that the platinum composition contains at least1 wt % of at least one precious metal selected from a group consistingof rhodium, gold, palladium and iridium, the platinum compositionpreferably containing at least 5 wt % rhodium as the at least oneprecious metal.

By adding the precious metals rhodium, gold, palladium and/or iridium,the mechanical properties of the platinum composition can be improved.In particular when adding rhodium, the high-temperature properties ofthe wire can be improved particularly advantageously.

Preferably, it may be further provided that the platinum compositionconsists of 2 wt % to 3.5 wt % tungsten, 5 wt % to 15 wt % rhodium, 0.05wt % to 1 wt % of the oxides of at least one non-precious metal selectedfrom the group consisting of (i) zirconium, (ii) aluminum and (iii)zirconium and at least one element selected from aluminum, yttrium andscandium, and, as the remainder, platinum including impurities, or theplatinum composition consists of 2 wt % to 3.5 wt % tungsten, 0.05 wt %to 1 wt % of the oxides of at least one non-precious metal selected fromthe group consisting of (i) zirconium, (ii) aluminum and (iii) zirconiumand at least one element selected from aluminum, yttrium and scandium,and, as the remainder, platinum including impurities.

As a result, it can be ensured that the platinum composition and thusthe wire have the desired properties.

With a composition according to the invention, tensile strengths of atleast 300 MPa, preferably at least 350 MPa, are achieved in therecrystallized state. Furthermore, the alloy has an elongation at breakof at least 12%, preferably at least 15%. Due to the stabilization withzirconia, this combination of properties is substantially retained evenif the material is subjected to temperatures greater than 1,300° C.

The material properties were determined in accordance with the standardDIN EN ISO 6892-1.

Furthermore, it may be provided that the wire has an elongation at breakof at least 12%, preferably at least 15%.

Such wires have excellent processability and are therefore particularlysuitable for production temperature sensors, for example. In addition,the wires are able to withstand the mechanical, thermal and chemicalstresses that occur, for example, when using a temperature sensor tomeasure car exhaust gas temperatures.

It may also be provided that the platinum composition contains between2.0 wt % and 3.0 wt % tungsten, preferably between 2.3 wt % and 2.8 wt %tungsten.

With these tungsten contents, a particularly good combination of tensilestrength and elongation at break is achieved without sacrificingcorrosion resistance.

The objects of the present invention are also achieved by a temperaturesensor, in particular a high-temperature sensor, for determining thetemperature, the temperature sensor comprising at least one such wire,preferably comprising two such wires.

Temperature sensors of this kind, in particular high-temperaturesensors, have the advantages mentioned for the wire and are particularlywell suited for use in areas with rapidly changing temperatures and alsoin vibrating environments, i.e. suited for use in the exhaust gas flowof motor vehicles.

It may be provided here that a thermal contact or a resistive structure,in particular a resistive layer, of the temperature sensor iselectrically conductively connected to the at least one wire forelectrical contacting, the temperature sensor preferably having two suchwires, and one end of a first of the two wires being electricallyconductively connected to one side of the thermal contact or theresistive structure or the resistive layer, and one end of a second ofthe two wires being electrically conductively connected to another sideof the thermal contact or the resistive structure or the resistivelayer.

Such a temperature sensor is usable particularly well in thermally,mechanically and chemically demanding environments.

The objects of the present invention are also achieved by a method forproducing a platinum composition comprising the following chronologicalsteps:

-   A) preparing a melt comprising between 2 wt % and 3.5 wt % tungsten,    up to 47.95 wt % of at least one precious metal selected from the    group consisting of rhodium, gold, iridium and palladium and    mixtures thereof, 0.05 wt % to 1 wt % of at least one oxidizable    non-precious metal selected from the group consisting of (i)    zirconium, (ii) aluminum and (iii) zirconium and at least one    element selected from aluminum, yttrium and scandium, and, as the    remainder, at least 50 wt % platinum including impurities,-   B) solidifying the melt to form a solid body,-   C) processing the solid body to form a volume body, and-   D) oxidizing the non-precious metals contained in the volume body by    a heat treatment in an oxidizing medium over a time period of at    least 24 hours at a temperature of at least 750° C., and-   E) processing the volume body to form a wire.

It may be provided here that a wire according to the invention isproduced, in particular drawn or pressed, by the method.

It may also be provided that, in step E), the solid body is firstductility-annealed at at least 1,300° C. for at least 1 hour and thendrawn or pressed to form a wire, an annealing process preferably beingperformed at a temperature between 1,000° C. and 1,200° C. before,between and/or after drawing or pressing.

As a result, the processing of the solid body to form a wire issimplified, and the resulting wire has high strength and a highelongation at break.

Lastly, the objects of the present invention are also achieved by amethod for producing a temperature sensor, characterized by producing awire by such a method and electrically contacting a thermal contact or aresistive structure or a resistive layer with at least one piece of thewire, preferably with at least two pieces of the wire.

The wire can be coated before electrical contacting.

The invention is based on the surprising finding that, by addingtungsten to a wire consisting of or containing a dispersion-hardenedplatinum composition, it is possible to significantly increase thetensile strength of the wire, while the elongation at break of the wiredoes not deteriorate or hardly deteriorates. The wire according to theinvention is thus usable for application as an electrical contactingwire for high-temperature sensors in cars, engines and other machines inwhich temperature changes, high temperatures and simultaneous vibrationsand mechanical stress as well as a chemically corrosive environmentcoincide.

Furthermore, less precious metal is used in wires according to theinvention, due to the use of tungsten instead of platinum (even if onlyto a small extent), and there is thus an additional financial advantage.

Exemplary embodiments of the invention are explained below without,however, limiting the invention.

Dispersion-solidified or dispersion-hardened platinum-tungsten alloys,i.e. platinum alloys containing 2.1 wt % tungsten (PtW2.1 DPH-A) and 2.4wt % tungsten (PtW2.4 DPH-A), respectively, and dispersion-hardenedplatinum (Pt DPH-A) known from the prior art for comparison, wereproduced. By adding 2.1 wt % or 2.4 wt % tungsten to adispersion-hardened platinum alloy, it was possible to maintain the verygood elongation at break of around 15%, while at the same time triplingthe yield strength and doubling the tensile strength.

The material was produced as follows:

The platinum compositions described in the following were produced by aningot with a weight of 2.5 kg being cast from the melt by vacuuminduction melting. Two different platinum compositions were produced inthis way, namely 2.1 wt % tungsten, 1800 ppm zirconium, 300 ppm yttrium,50 ppm scandium and, as the remainder, platinum including impurities(PtW2.1 DPH-A) and 2.4 wt % tungsten, 1800 ppm zirconium, 300 ppmyttrium, 50 ppm scandium and, as the remainder, platinum includingimpurities (PtW2.4 DPH-A). The non-precious metals zirconium, yttriumand scandium were added during the vacuum induction melting.

The ingot was cast in a vacuum induction melt, then rolled to 2.5 mm andoxidized (900° C. for 24 days) until complete transformation of thenon-precious metals Zr, Y and Sc into the oxides thereof. A ductilityannealing process (1,400° C. for 6 hours) was then performed, and withan intermediate annealing process in a continuous furnace at 1,100° C.at 1 mm and 1 m/min, the material was drawn to final size (wire diameter0.25 mm), and a final annealing process was performed in the continuousfurnace at 1,100° C. at a drawing speed of 1 m/min. The temperature of1,100° C. was chosen because the material recrystallizes completelywithin a short time at this temperature.

The reference material Pt DPH-A was similarly produced, only theaddition of tungsten was omitted.

The mechanical properties were then determined experimentally in atensile test.

Wires with a diameter of 0.252 mm were produced from the platinumcomposition PtW2.1 DPH-A, and wires with the same diameter of 0.252 mmwere produced from the platinum composition PtW2.4 DPH-A.

In addition, wires with a diameter of 0.246 mm were produced from theplatinum composition Pt DPH-A for comparison.

For the wires of platinum compositions PtW2.1 DPH-A and PtW2.4 DPH-A,the following parameters were used in the experiment setup to determinethe mechanical properties listed below: Initial force 10 N/mm², speedfor yield strength 1 mm/min, speed for modulus of elasticity 1 mm/min,and test speed 10 mm/min. For the wires of platinum composition Pt DPH-Awith 0.246 mm, the following parameters were used: Initial force 5N/mm², speed for yield strength 1 mm/min, speed for modulus ofelasticity 1 mm/min, and test speed 10 mm/min. The low initial forceswhen clamping the samples in the measuring apparatus do not change thestructure of the wires and therefore have no influence on themeasurement results.

For the wires of platinum compositions PtW2.1 DPH-A, PtW2.4 DPH-A and PtDPH-A with a 0.25 mm diameter, five wires of each were measured and usedfor the following values by averaging and calculating the standarddeviations (s). Furthermore, the mechanical properties of the wires weredetermined after an additional further annealing process for a period of1 hour at 1,400° C. to test the temperature stability at extremely hightemperatures.

TABLE 1 Measured values for the mechanical properties of the measuredwires Pt DPH-A 0.246 mm: R_(p0.2) 64.5 N/mm² (s = 1.2 N/mm²) R_(m) 174.7N/mm² (s = 3.1 N/mm²) F_(m) 8.3 N (s = 0.1 N) A 100 mm 13.18% (s =1.92%) PtW2.1 0.252 mm: R_(p0.2) 192.7 N/mm² (s = 0.8 N/mm²) R_(m) 353.6N/mm² (s = 0.7 N/mm²) F_(m) 17.64 N (s = 0.03 N) A 100 mm 16.51% (s =0.75%) PtW2.4 0.252 mm: R_(p0.2) 209.1 N/mm² (s = 3.2 N/mm²) R_(m) 373.1N/mm² (s = 2.3 N/mm²) F_(m) 18.61 N (s = 0.11 N) A 100 mm 16.82% (s =0.32%) PtW2.1 0.252 mm, additional annealing 1,400° C. 1 h: R_(p0.2)182.6 N/mm² (s = 0.3 N/mm²) R_(m) 344.9 N/mm² (s = 0.4 N/mm²) F_(m)17.20 N (s = 0.02 N) A 100 mm 17.27% (s = 0.82%) PtW2.4 0.252 mm,additional annealing 1,400° C. 1 h: R_(p0.2) 195.0 N/mm² (s = 3.2 N/mm²)R_(m) 359.7 N/mm² (s = 0.1 N/mm²) F_(m) 17.94 N (s = 0.01 N) A 100 mm16.44% (s = 0.23%)

R_(p0.2) is the yield strength or 0.2% proof stress, R_(m) is thetensile strength, F_(m) is the maximum force, A 100 mm is the elongationat break, and s is the standard deviation from the mean. The tensiletests were performed on a Zwick Roell Z250 floor-standing testingmachine.

The advantageous technical effect of the wires according to theinvention containing or consisting of the platinum composition, whichcan be seen in the high tensile strength with a simultaneously highelongation at break, was achieved by a suitable combination of platinumand tungsten and oxide dispersion hardening (on the basis of zirconia,but said effect can also be expected for alumina and is therefore alsotransferable to alumina). The amount of tungsten and oxide formers waschosen to significantly improve the mechanical properties (in particularin direct comparison with a Pt DPH-A alloy without the addition oftungsten), without reducing the oxidation or corrosion resistance belowa critical level, so that the material of the wire does not degrade and,in the worst case, fail under operating conditions (for example, in hotexhaust gases of an internal combustion engine).

The high elongation at break is very unusual for dispersion-hardenedplatinum and dispersion-hardened platinum alloys. These are usually muchmore brittle. The high elongation at break is presumably favored by theproduction from the melt and by the internal oxidation of thenon-precious metals zirconium, aluminum, yttrium and/or scandium fordispersion-hardened platinum alloys. In particular, in the embodimentwith zirconia stabilized by yttrium and/or scandium, this process isaccompanied by stabilization of the cubic high-temperature phase of thezirconia by yttrium oxide and/or scandium oxide such that said phase isstable over the entire temperature range. Non-stabilized zirconia existsin three crystalline modifications with transitions from monoclinic totetragonal at about 1,170° C. and finally to cubic crystal structure atabout 2,370° C.

The features of the invention disclosed in the above description, aswell as in the claims, drawings and exemplary embodiments, may beessential both individually and in any combination for realizing theinvention in its various embodiment.

1. A wire for electrically contacting temperature sensors, the wireconsisting of at least 50 wt % of a platinum composition, the platinumcomposition containing 2 wt % to 3.5 wt % tungsten, up to 47.95 wt % ofat least one precious metal selected from the group consisting ofrhodium, gold, iridium and palladium and mixtures thereof, 0.05% to 1 wt% of oxides of at least one non-precious metal selected from the groupconsisting of (i) zirconium, (ii) aluminum and (iii) zirconium and atleast one element selected from aluminum, yttrium and scandium, and, asthe remainder, at least 50 wt % platinum including impurities.
 2. Thewire of claim 1, wherein the platinum composition isdispersion-hardened.
 3. The wire claim 1, wherein the wire has anelongation at break of at least 12%.
 4. The wire of claim 1, wherein thetotal proportion of the impurities in the platinum composition is atmost 1 wt %.
 5. The wire of claim 1, wherein the wire consists of atleast 90 wt % of the platinum composition, or the wire consists of theplatinum composition except for an outer coating or plating, or the wireconsists of the platinum composition.
 6. The wire of claim 1, wherein atleast 50 mol. % of the oxides of the at least one non-precious metal iscubic zirconia stabilized with yttria or scandia or yttria and scandia.7. The wire of claim 1, wherein the platinum composition is produced bymelting metallurgy and is subsequently oxidized by a temperaturetreatment in an oxidizing medium such that the non-precious metalscontained in the platinum composition are at least 90% oxidized orcompletely oxidized.
 8. The wire of claim 1, wherein the platinumcomposition contains at least 80 wt % platinum including impurities andup to 17.95 wt % rhodium.
 9. The wire of claim 1, wherein the platinumcomposition contains at least 1 wt % of the at least one precious metal.10. The wire of claim 1, wherein the platinum composition consists of 2wt % to 3.5 wt % tungsten, 5 wt % to 15 wt % rhodium, 0.05 wt % to 1 wt% of the oxides of at least one non-precious metal selected from thegroup consisting of (i) zirconium, (ii) aluminum and (iii) zirconium andat least one element selected from aluminum, yttrium and scandium, and,as the remainder, platinum including impurities, or the platinumcomposition consists of 2 wt % to 3 wt % tungsten, 0.05 wt % to 1 wt %of the oxides of at least one non-precious metal selected from the groupconsisting of (i) zirconium, (ii) aluminum and (iii) zirconium and atleast one element selected from aluminum, yttrium and scandium, and, asthe remainder, platinum including impurities.
 11. The wire of claim 1,wherein the platinum composition contains between 2.0 wt % and 3.0 wt %tungsten.
 12. A temperature sensor, the temperature sensor comprising atleast one wire according to claim
 1. 13. The temperature sensor of claim12, wherein a thermal contact or a resistive structure of thetemperature sensor is electrically conductively connected to the atleast one wire for electrical contacting and one end of a first of thetwo wires being electrically conductively connected to one side of thethermal contact or the resistive structure, and one end of a second ofthe two wires being electrically conductively connected to another sideof the thermal contact or the resistive structure.
 14. A method forproducing a platinum composition comprising the following chronologicalsteps: A) preparing a melt comprising between 2 wt % and 3.5 wt %tungsten, up to 47.95 wt % of at least one precious metal selected fromthe group consisting of rhodium, gold, iridium and palladium andmixtures thereof, 0.05 wt % to 1 wt % of at least one oxidizablenon-precious metal selected from the group consisting of (i) zirconium,(ii) aluminum and (iii) zirconium and at least one element selected fromaluminum, yttrium and scandium, and, as the remainder, at least 50 wt %platinum including impurities, B) solidifying the melt to form a solidbody, C) processing the solid body to form a volume body, D) oxidizingthe non-precious metals contained in the volume body by a heat treatmentin an oxidizing medium over a time period of at least 24 hours at atemperature of at least 750° C., and E) processing the volume body toform a wire.
 15. The method of claim 14, wherein processing the volumebody to for the wire comprises drawing or pressing.
 16. The method ofclaim 14, wherein in step E), the solid body is first ductility-annealedat a temperature of at least 1,300° C. for at least 1 hour and thendrawn or pressed to form the wire.
 17. The method of claim 16, whereinannealing at a temperature between 1,000° C. and 1,200° C. is carriedout before and/or after drawing or pressing.
 18. A method for producinga temperature sensor, the method comprising: producing a wire by amethod according to claim 14, and electrically contacting a thermalcontact or a resistive structure or a resistive layer with at least onepiece of the wire.
 19. The wire of claim 1, wherein at least 80 mol. %of the oxides of the at least one non-precious metal is cubic zirconiastabilized with yttria or scandia or yttria and scandia.